Depression is believed to be an affective disorder, a mental disease symptom that is mainly characterized by a depressed mood. Clinically, it is expressed by a series of symptoms, including depressed mood, bradyphrenia, less words, decreased activity and loss interest in work etc. As reported by the WHO, depression has become the fourth largest disease in worldwide. By 2020, it will likely to become the second largest disease, just next to heart diseases. Now, there are about 26 million depression patients in China, only 10% of which, however, can have opportunity to get normal drug therapy. Hence, anti-depressive drugs will certainly have a huge potential market.
As suggested by numerous researches, the change of nerve center monoaminergic neurotransmitters, dopamine and cholinergic, variation of their relevant receptor function and neuroendocrine dysfunction were likely to play an important role in occurrence and development of depression. Up to now, a principle for treating the depression should be focused on adjusting the content of monoamine neurotransmitters in hypothalamus, their receptor function and restoring normal neuroendocrine.
Nowadays, drug therapy is still the main manner for treating depression. It has been confirmed by literatures that the pathogeny of depression is complex, associated with many factors, e.g. social psychology, heredity, biochemical changes of human body and neuroendocrinology. The anti-depressive drug is possible to have various kinds of targets, e.g. receptors, concentration of monoamine neurotransmitters and cytokine. Different anti-depressive drugs take effect through different targets. The first generation of anti-depressive drugs belonged to monoamine oxidase inhibitors. However, the selectivity and irreversible inhibitory effect on enzyme thereof lead to toxic liver injury, which has certain toxic and side effects; therefore, it is gradually replaced by tricyclic anti-depressive drugs. Such common-used medicines include doxepin, amitriptyline and clomipramine etc. Although having a better therapeutic effect on endogenous depression, especially having more than 80% of efficacy for emotional depression, loss of interest and pessimism, these drugs are considered to have higher cardiac toxicity and more adverse reactions. In the late 1980s, selective 5-HT reuptake inhibitor (SSRI) emerged as a kind of novel anti-depressive drug. By now, they have been used as a common first-line anti-depressive drug in Europe and USA, because they maintain the classical effect of anti-depression, and significantly reduce adverse reactions caused by other receptors. Such common-used medicines include fluoxetine, paroxetine, sertraline, citalopram and fluvoxamine etc. They are absorbed through stomach and intestine and metabolized in live, thus cause gastrointestinal dysfunction, and some of them further cause sexual dysfunction. Also, clinical studies showed that it was hard to achieve a satisfactory effect for those synthesized drugs which was designed to direct to single target. Up until now, there has not been developed the ideal anti-depressive drug with better efficacy and less toxic and side effects.
Chinese patent application (Appl. No.: 201010169679.9) disclosed a compound of N-isobutyl-5′-methoxy-3′,4′-methylenedioxy cinnamamide, which was a alkaloids extracted from Piper laetispicum C. DC, a plant of piperaceae. Its structure is presented below. As shown in animal experiments, the compound of N-isobutyl-5′-methoxy-3′,4′-methylenedioxy cinnamamide had significant anti-depressive effect.
